1971-1974 AMC Javelin AMX 401

Slightly redesigned taillamps distinguished
the 1972 AMC Javelin AMX 401 externally, but there were more important changes under the
hood. As were its Motown rivals, AMC was scaling back performance under
pressure from increasingly stringent exhaust-emission standards and oppressive
insurance rates.

So the AMC 304-cubic-inch V-8 became the
standard Javelin AMX engine for ’72; the 360 was now an option along with the
401. Underscoring this retreat, the manufacturers began to list net horsepower
ratings -- the engine with all its accessories as installed in the car -- rather than
gross horsepower -- essentially the engine free of encumbrances.

The 304 was listed at 210 horsepower in
’71, but only 150 under the new rating system in ’72. Estimates of the 304’s
gross horsepower ran around 200, but regardless, the 304 proved a
disappointment to buyers pursuing more horsepower for their Javelin AMX. Most
opted for the larger 360, a $188 extra. This engine was down to 175 horsepower
with the two barrel, 195 with a four barrel and single exhaust, and 220 for the
four barrel with dual exhaust. Compression was down to 8.5:1 for more efficient
use with the unleaded fuels that were now required. Included with the 360 were
E70×14 Goodyear Polyglas tires and other features.

The 401-cubic-inch V-8 remained an option
and was now rated at 255 horsepower at 4600 rpm.